Guidelines for the protective role of forests in avalanche formation

Summary

1.

The significance and value of avalanche protection forests for our alpine valleys The value of indispensable avalanche protection forests can be measured by comparison of their cost with the cost of construction of avalanche struts, which are, however, only a very unsatisfactory substitute.

2.

Varying importance and need for tending of avalanche protection forests Avalanche protection forests which are absolutely necessary are specified in the new Swiss Forestry Laws as forests which fulfil a particular protective function: they are forests on steep slopes “where a direct threat to people or substantial property arises from the dangers of avalanches, landslides, erosion, rock or mudslides”. In such cases the cost of upkeep of these forests is covered, in the main part, by public revenues. Other protection forests—for example those in remote valleys which are not populated all the year round—only qualify for minimum tending measures: “Measures of minimal care and upkeep of protective functions are those that are limited to securing a sustainable stability of stock; any wood is to be used on the spot or left lying, provided that this incurs no danger”. For this particular project category, a practical guide has been developed for planning and implementing the necessary tending measures.

3.

How the forest protects against avalanche starts and the necessary silvicultural goals The main protective mechanisms of the forest to prevent avalanches will be presented. The necessary silvicultural goals are described in detail in the above-mentioned guide on minimal tending measures. Minimal as well as desirable condition of stands is given with regard to the stability requirements for every type of site and specifically for the most important characteristics of stands. In the protection forest category “minimal tending measures” it suffices to fulfil minimal goals; here the ideal goals have a directing function, somewhat like a compass. In protection forests with important protective functions, however, the ideal goal is striven for, which requires correspondingly more intensive tending measures.

-In view of the fact that subalpine forest development is outside human control, it is a question of early support for stabilizing tendencies and prophylactic measures which combat destabilizing tendencies in development, i.e. providing natural help aimed at self-help.

-It is essential to respect the frequently changing mosaic of sites and this requires a high level of observation and good observational abilities.

-By comparison with the original natural forest, the present day protection forest is mostly anthropogenically influenced secondary forest. The disturbances in stability of autoregulating mechanisms that have been caused must be identified and corrected.

-Stability maintenance of mountain forests should be as natural as possible and based on the standards of the natural forest populations.

5.

Prerequisites and framework for functional tending of avalanche protection forests

-The principal problem in the tending of protection forest today stems from game damage. This must be reduced to a level where all tree species native to the site in question can exist without additional protective measures.

-The signs of new forest decline (loss of vitality) must be taken seriously and we must develop a less technocratic manner to deal with this natural foundation of life.

-The long-term means must be secured to finance the necessary tending measures. As far as the public sector is concerned, the controllability of these tending measures must be guaranteed.